Cellar doors, storm doors, trap doors, and hatchways have provided ingress and egress for basements of dwelling structures for over a century. Doorways such as these have been commonly added to buildings as an after-thought and accordingly have been configured in such a manner so as to reduce the amount of construction involved. Further, these types of doorways have generally provided access to a safe haven for occupants during thunder showers, blizzards and tornadoes. Accordingly, it is desirable for these doorways to have a low profile in order to reduce the adverse effects brought on by the elements.
Inventors have focused upon improvements to the traditional storm door for over 100 years. W. S. Castor, U.S. Pat. No. 270,635, disclosed in 1883 a counter-balanced storm door having a foot operated releasing mechanism. The Castor storm door was made out of wood and incorporated a mechanical swinging element/spring assembly to assist movement of the door into a standard upright position.
Additional patents have outlined the evolution of the conventional storm door adding various improvements thereto. Golden, U.S. Pat. No. 443,962, discloses a device for raising and lowering cellar doors. A crank arm in the form of a bent rod is used to urge a wooden door from a closed position to an open position. Similarly, Baldwin, U.S. Pat. No. 794,968, discloses a wooden cellar door in which a counter balanced weight is used to urge the door into an upright position. Lyons, U.S. Pat. No. 2,174,989, discloses a metallic dual door hatchway for providing access to the basement of a structure. Lyons further discloses that a lock, handle, and metallic hinge mechanism may be used in accordance with the hatchway door structure.
The Lyons disclosure is quite similar to FIG. 1 of the present invention which shows a dual door metallic storm door. FIG. 1 shows that the conventional storm door has changed little over the last 50 years. In the conventional design, as shown, a pair of heavy metallic doors cooperate to form an entryway into a basement of a dwelling. The doors and assembly are not insulated and provide little thermal protection from the environment.
Howle, U.S. Pat. No. 3,849,951, discloses a slidable storm door and associated door frame for mounting above a storm cellar. A roller mechanism cooperates with the dual door structure to move one door within a recess provided by the other. Accordingly, the second door or "protective panel" functions as the door assembly. A locking means is also provided.
Lyons Sr., U.S. Pat. No. 4,873,791, discloses in his patent dated Oct. 17, 1989, a conventional dual door storm door assembly incorporating a torque rod and counter balancing hinge assembly. The torque rod and hinge assembly cooperate to provide linear torque to the storm doors such that they may be "balanced" in any position, i.e., between 0.degree. and 90.degree. of opening. Lyons, Sr. seeks to overcome the problems of conventional metallic doors which are heavy and cumbersome to operate.